Ozone Depletion

By Krishna Kalyankasture

Ozone LayerOzone layer is present at

an altitude of 25 km ,in stratosphere

It is about 3 millimeters(mm) thick.

The layer absorbs 97.99% of sun’s high frequency rays.

It protects life on the earth.

Ozone DepletionOzone depletion means reduction of ozone layer in stratosphere.It is measured in terms of ,level of total ozone column above the point on earths surface.The depletion of ozone is observed using

instrument called Total Ozone Mapping Spectrometer ( TOMS).

It is expressed In Dobson units , abbreviated as ‘DU’.

Ozone cycle1)Oxygen molecules are

photolized yielding 2O2 atoms.

2)Ozone and oxygen atoms are continuously being interconverted as solar UV rays breaks ozone and oxygen atom reacts with another oxygen molecule .

Ozone cycleOzone is lost by

reaction of O2 atom or ozone molecule with each other ,or some trace gas such as chlorine .

The interconversion process converts UV radiation into thermal energy, heating the stratosphere.

Depletion How It Occurs

Ozone depletion mainly occurs by:- Chlorine (Cl∙) Chlorine oxide (Clo) Chloro Fluro Carbon (CFC) Nitrogen oxide (No∙) Bromine (Br∙) Chloro Fluro Chloride (Cfcl3) & electromagnetic

Radiation[The dot is common notation to indicate that this

species have an unpaired electron and thus are extremely reactive. ]

Chlorine Depletion CycleReaction of O3(ozone) with chlorine –Cl∙ + O3 Clo + O2The chlorine atom changes an ozone molecule to

ordinary oxygen

Reaction of O3 with chlorine oxide -Clo + O3 Cl∙ + 2O2 The Clo from previous reaction destroys a second

ozone molecule and recreates the original chlorine can repeat the first reaction and continue to destroy ozone.

Sources of chlorine and ozone Depletion

Ways Of Depletion (CFC depletion)

Air Conditioners[AC] & refrigerator causes ozone depletion.

They give out Chloro Fluro Carbon (CFC).

CFCs are also used in some extinguishers and in spray cans.

CFCs cause depletion especially in cold climate

CFCs remain in atmosphere for decades.

Ways Of Depletion(No & Br )∙ ∙

Nitrogen oxide (No∙) & Bromine (Br∙) get released in atmosphere by industries, furnaces and many other human activities .

Now a days the levels of Nitrogen oxide (No∙) Bromine (Br∙) are increased .

No & Br convert’s ozone (O3) into ordinary oxygen.

Ways Of Depletion Chloro Fluro Chloride (Cfcl3) & electromagnetic Radiation

Reaction of Chloro Fluro Chloride (Cfcl3) & electromagnetic Radiation-

Cfcl3 + electromagnetic Radiation Cl∙ + Cfcl2

Now this released chlorine will

continue its depletion cycle , and lead to more depletion .

Sources That Harm Ozone Layer

Effects Of UVThey causes crop failure,They cause skin cancer,They can go directly through water ending up

all aquatic life,UV rays can cause more sun burn,They can damage our eyes and can increase

in people becoming blind.

Effects Of UV They harm all living world.

Ozone HoleScientist first observed an ozone hole over

Antarctica in the mid-1980

And in 2011 –for first time – an ozone hole opened over the northern Arctic

There are signs that ozone layer is getting thinner all over the earth .

Ozone Hole The loss of ozone layer occurs when more

ozone is being destroyed than nature is creating.

Conclusion From this I conclude that Ozone Depletion is very

dangerous . Cl , Clo , CFC , Br , No , Cfcl3 are main causes

of it ,so for controlling the ozone depletion the emission of these substances must be stopped.

If ozone depletion is not stopped life on earth will end forever

we should make control on A.C. , refrigerator , industries , vehicles and human activities which causes ozone depletion

THANK

YOU